Institute of Mining, Ural Branch, Russian Academy of Sciences, Ekaterinburg, Russia:

Krinitsyn R. V., Researcher, Roman_krinicyn@mail.ru
Khudyakov S. V., Senior Researcher, Candidate of Engineering Sciences

At Magnezitovoye mine, Magnezit, the reserves of magnesite are processed by the chamber system of development in layers in ascending order with the use of a dry bookmark of the worked out space. When the unit No. 1 was worked out, cracks in the subvertical direction were revealed, signs stretching for tens of meters. Cracks are both tightly closed contacts, and friction-filled rubbers. There were lobes, permeated with one, two or more such cracks, especially with the effects of explosions. Explosive work of the nano-decomposed damage of the configuration of the ends, reducing their geometric dimensions, observance of which affects the bearing capacity of the pillars. Even a slight decrease (change) of the geometric parameters of the target can be reduced for the rest of the area, which in turn can lead to the destruction of the whole. To solve one of the problems of ensuring the sustainability of targeted programs using software using anchor installations and / or injection. Several variants of the location of the crack (violation) in the whole were considered:
1. Option, when the crack goes to the wall of the lintel above its base (soles)
2. Option when the crack crosses this ground.
The investigated parameters of fastening narrow ribbon pillars in the presence of subvertical cracks in them, which have an opening of 3 mm or more. Studies have made it possible to establish the necessary number of anchors for 1 m² for fixing such cracks to ensure the stability of the pillar, and the possibility of using resin injections. Features resin is that the binder can penetrate even into small cracks, but only at a shallow depth. These measures will ensure the sustainability of the structural elements of the development system, as well as improve the safety of people employed in underground work.

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